Even before the advent of automobiles, air-cooling systems of sorts were available for vehicles such as horse-drawn carriages. One example was a system that involved placing ice blocks in a holder under a carriage where air, blown by a fan on the carriage axle, would move across the ice blocks towards the passengers.
Air cooling systems, better known as air conditioning (A/C) systems, for present day automobiles have become much more complex. Today's automotive air conditioning systems generally include an evaporator, a compressor, a condenser, and an expansion valve fluidly connected together by refrigerant lines. The compressor receives refrigerant at a low pressure as a vapor from the evaporator. The compressor then compresses the vaporous refrigerant to a higher pressure, and sends it to the condenser. The condenser cools and liquifies the refrigerant and sends it to the expansion valve. At the expansion valve, the pressure and temperature of the refrigerant drops, usually quite drastically. After the expansion valve, the cooled refrigerant returns to the evaporator where it evaporates, causing the surrounding space of the evaporator to be cooled. This cycle is continuously repeated as the A/C system is in operation.
In order to ease the serviceability of an automotive A/C system, it is desirable to ease the detachability of the refrigerant lines from the various system components. However, it is not desirable to allow the refrigerant to escape from within the A/C system, so particular attention should be given to ensuring that connections between refrigerant lines and the various system components are sufficiently sealed. One way that such connections have been made in the past is with pad-style fittings as illustrated in FIG. 5.
As shown in FIG. 5, two refrigerant lines 110 and 111 are connected to a component 116 of an A/C system, where, for example, line 110 can be an output line and line 111 can be an input line. The ends of lines 110 and 111 are engaged in respective ports 120 and 121 of the component 116, so as to penetrate through a face 117 of the component 116. Each of lines 110 and 111 includes a respective annular bead 122 and 123. An anchor plate 114 is provided, which bears on the annular beads 122 and 123 so as to compress respective o-ring seals 124 and 125 into respective annular seatings 126 and 127. The annular seatings 126 and 127 define respective terminal radial enlargements of the ports 120 and 121 adjacent to the face 117. A hex nut 118 fastened to a threaded stud 112 is provided for securing the anchor plate 114 against the beads 122 and 123.
Prior types of connectors such as the one described above are often referred to as pad-style IMACA (International Mobile Air Conditioning Association) 305 connectors. IMACA 305 is a standard for threaded connections such as the connector shown in FIG. 7. It will be noted that the connector in FIG. 7 includes a threaded swivel nut 130 that is not present in the pad-style connector shown in FIG. 5. Because the threaded swivel nut 130 must be threaded into the threaded female portion 132, these threaded connections are relatively cumbersome to assemble. Thus, the pad-style version of the IMACA 305 discussed above was developed to provide a connector that is less cumbersome to assemble, while at the same time maintaining IMACA 305 standard dimensions.
However, despite the increased ease with which the pad-style fittings can be assembled, they are known to suffer high failure rates. The connection failures in the pad-style connectors are very often caused by the seals not seating properly during assembly. This is a disadvantage of the pad-style connectors compared to the threaded connectors. On the threaded connectors, the threaded swivel nut acts as a pilot to align the parts, providing for the proper positioning of the seal. While the pad-style connectors are easier to assemble as a result of not having the threaded swivel nut, they also lack the piloting feature provided by the swivel nut. As a consequence, slight misalignments can occur when assembling a connector such as the one shown in FIG. 5, resulting in the seal not seating properly.
When a seal does not seat properly during assembly, a portion of the seal becomes extruded, or “pinched out” of position. An example of this is shown in FIG. 6, where an extrusion, designated generally as 128, of seal 124 can be seen due to the seal 124 becoming improperly seated during assembly. The seal 124 is held out of alignment due to the pressure of anchor plate 114 bearing down on the bead 122, which in turn bears down on the extruded portion 128 of seal 124, holding it between the bead 122 and the face 117. When this happens, the misaligned seal 124 can be difficult to visually detect due to visual obstructions, such as the anchor plate 114. Since the seal 124 is misaligned, a slow leak in the A/C system can result. Not only is a leak in the A/C system undesirable, but such leaks can be expensive and time-consuming to troubleshoot and repair, and can also have adverse environmental implications.
As a result of the problems with seals not seating properly with the pad-style connectors, alternative types of connectors have been developed in the art in an effort to provide a connector that is simple to assemble and reliable. This trend has led to the development of connectors that no longer adhere to the IMACA 305 geometry. As a result, such connectors tend to be considered more specialized from a manufacturing standpoint, and therefore require an increased amount of documenting and/or retooling as compared to connectors that comply with IMACA standard dimensions. Thus, the expense of such connectors tends to increase as well.